I've only recently started seriously considering haste. Mostly I've got what I have now based on available upgrades and using stat weightings from places like DwarfPriest. I'm trying to actually understand why the weightings are such and also take stuff like soft caps into account now though and was having trouble getting my head round haste.

433 is the amount of Haste Rating you need to hit the haste soft cap (50%), where the GCD is reduced to its minimum of 1.0s, when Borrowed Time and Enlightenment are active. Haste is multiplicative (although haste rating is additive), and each value you're multiplying is (100+Haste bonus)/100; Borrowed Time's 25% haste contributes 1.25 to the function. So when Borrowed Time and Enlightenment are active, you have a base of 1.25*1.06 = 1.325, or 32.5%, haste. Dividing 1.50 (the soft cap) by 1.325 (since Haste is multiplicative, not additive) gives you 1.132, or 13.2%, that you need to make up in Haste Rating. At 32.79 HR per 1% haste, that's 432.8 HR – 433 rounding up, since you can't get fractional HR.

As for raid buffs, I prefer strongly to avoid making gear and healing decisions based on raid composition. Anything beyond what I can do myself is a pleasant added bonus, but not something I can rely on. Food buffs can get you an additional 40 HR, and if you're willing to forego a flask, Elixir of Lightning Speed will get you another 45 HR, which is about 2.6% haste between them. And yes, the Egg procs help get up there, but like class buffs they're unreliable, and you'll eventually want to upgrade past the Egg.

Does that all make sense?

Here's me: http://eu.wowarmory.com/character-sheet.xml?r=A…

By my calculations with my haste, plus the PW:S haste buff and raid buffs I'm not far off the soft cap. Well over it if the Egg proc is included. Unless I've got things wrong.

Where does 433 come from?